Nuclear medicine is a unique medical specialty wherein radiation is used to acquire images which show the function and anatomy of organs, bones or tissues of the body. Generally, low-level radiopharmaceuticals are ingested or injected into the body and carried to the specific organs, bones or tissues. Gamma photon emitted by the radiopharmaceuticals are then captured by a gamma camera of the imaging device and used to prepare images of the target. In this way, specific organs, bones or tissues and/or functions thereof can be studied with minimal impact upon the patient or subject being studied.
In order to prepare images, however, it is necessary to calibrate and ensure the accuracy and proper working order of the nuclear imaging device to be used. This is commonly performed by the use of calibration instruments, known as phantoms. Generally, phantoms are structures having known parameters, which can include, but are not limited to, specific dimensions and/or radiation levels. Accordingly, an image of a phantom produced by a nuclear imaging device can be compared with the actual phantom to determine, for example, image quality, background radiation levels, attenuation information, etc.
In addition to their use as calibration devices, phantoms can also be used for other purposes such as, for example, simulating anatomical conditions for purposes of training individuals to properly use a medical imaging device and/or for training individuals how to read images and/or render diagnoses from the images produced by a medical imaging device. Accordingly, there are various types of phantom and the particular phantom to be used in a simulation depends on a number of factors, which include but are not limited to: specific anatomical area to be studied, e.g., heart, lungs, etc., specific anatomical condition/anomaly to be studied, e.g., normal vs. diseased tissue, etc., and environment, e.g., calibration vs. training. Indeed, phantoms currently range from mere computer software programs, to simple cylindrical devices primarily used for calibration purposes, to more complex mechanical devices that can include pumping mechanisms for mimicking moving body parts, e.g., the human heart.
While there are known several types of phantom for simulating anatomical conditions, one mechanical-type is described in U.S. Pat. App. Pub. No. 2003/0220718 A1, which published application is incorporated herein by reference in its entirety. The phantom disclosed in that application generally relates to a dynamic cardiac phantom for simulating the beating of a human heart and includes inner and outer elastomeric members defining a void therebetween; the void is intended to mimic the myocardium of the human heart and is capable of being filled with a radiative tracer. The dynamic cardiac phantom, thus, can be used to simulate and image the systolic and diastolic functions of the human heart. Another dynamic cardiac phantom is disclosed in U.S. Pat. App. Pub. No. 2003/0045803 A1 which published application is also incorporated herein by reference in its entirety.
While the dynamic cardiac phantoms described in U.S. Pat. App. Pub. Nos. 2003/0220718 A1 and 2003/0045803 A1 may be useful for accomplishing their intended purposes, it is also desirable to simulate other anatomical functions and/or characteristics of organs, tissues or bones. For example, because diseased or abnormal tissue can tend to more rapidly “wash-in” or more rapidly “wash-out” certain tracers when compared with normal, non-diseased tissue, it can be desirable to monitor tracer wash-in and wash-out for diagnostic purposes. Accordingly, it is also desirable to simulate wash-in and wash-out.
What is needed then is a phantom that is capable of simulating tracer wash-in and washout, e.g., radiative tracer, uptake, residence, and/or processing by organs, tissues or bones.